Before Cheir is treatable, the many lacerations already present on the affected organ must be sutured. After all of the lacerations have been sutured, Cheir will finally appear.
Immature Cheir is to be treated almost exactly like Kyriaki, keeping in mind there are a few minor differences. The only way to defeat Immature Cheir is with continued lasering, like Kyriaki; however, Cheir requires much more exposure to the laser compared to Kyriaki. There will be 3-4 "waves" of Immature Cheir.
As the final wave of Immature Cheir appears, 2 of them will fuse to form a Fused Cheir. This takes even more laser exposure than an Immature Cheir to be defeated, and is capable of creating 6 lacerations in an asterisk pattern.
Some Cheir operations will feature Immature Mutated Cheir for the second wave. The mutated forms only have different attack capabilities; everything else remains the same. These attacks include forming a large laceration and forming tumors.
Whenever Cheir is hit with the laser, it will be pushed back slightly in the opposite direction. This can be used as a tactic against Cheir by "pushing" it off of the affected organ, since Cheir cannot attack if it isn't on the organ.
The laser can also be held immediately in front of a Cheir that's travelling in a straight line, such that the Cheir will keep bumping into the laser, taking damage each time.
In addition, tapping the A button and using the laser in short bursts tends to be equally effective while reducing the amount of laser battery used up.
Cheir is immune to laser damage for a short while after an "Ok" is gained. Take this brief moment to tend to wounds or vitals instead of wasting the laser.
Applying antibiotic gel will drastically reduce Cheir's movement speed for a short period of time.
For those gunning for an XS, one may opt to keep Mutated Cheir alive longer to increase the Chain from the wounds created.